In recent years, many display devices with liquid crystal are used in order to downsize a display device of a picture, and particularly, a liquid crystal display device comprising an active matrix panel with TFT has been studied greatly since higher quality of the picture can be obtained easily as compared with a simple matrix type liquid crystal display device.
Meanwhile, in order to downsize a read device of an original picture, the device is known wherein the picture can be read by putting the original closely on an image sensor which is arrayed two-dimensionally without using the scan system of the original or the sensor section.
A device is proposed for downsizing the whole device and improving the operationalization by reading the original picture and obtaining picture data as well as displaying the picture with the combination of the above-mentioned display device and read device of the picture.
This kind of device, as disclosed, for example, in Japanese Unexamined Patent Publications No. 4-282609, is composed in the arrangement of a transparent substrate with an image sensor on the backside of a transparent substrate with TFT and a transparent pixel electrode in a liquid crystal display device. In the liquid crystal display device, while reading an original picture, the original picture is read by making all the pixels in liquid crystal a transmission state, irradiating backlight over the whole original, and detecting the strength of reflected light from the original.
A device for displaying and reading a color picture comprises a back light source of white light and a micro color filter with the field for transmitting the light of red, green or blue at each pixel, and displays the color picture by controlling the light transmittance of each color, while the device reads the color picture by detecting the quantity of reflected light of each color from the original. That is, the display and read of a pixel (hereinafter referred to as `color pixel`) of a predetermined color are executed by joining three pixels (each pixel is hereinafter referred to as `simplex pixel`) of red, green and blue.
However, in the composition of arranging a transparent substrate with TFT and a transparent substrate with an image sensor in layers as described above, the visibility and the read property of the picture are deteriorated since the transmittance of backlight and reflected light from the original is decreased
As disclosed, for example, in Japanese Unexamined Patent Publications No. 5-145699, a read device of a picture with complete control of open and shut is proposed for a means of preventing the deterioration of such visibility. However, in this case, the problem is that the complication of structure and the deterioration of reliability are caused by providing the mechanism of open and shut, and additionally, the deterioration of operationalization is caused by needing the operation of open and shut in each execution of reading the picture.
It is written in the above-mentioned Japanese Unexamined Patent Publications No. 4-282609 that TFT and an image sensor may be provided actually on the same transparent substrate although the concrete constitution is not described However, generally in the case of constituting in this way, since it is necessary to form not only the wiling pattern for controlling TFT for display but also the wiring pattern for controlling an image sensor on the same substrate, the deterioration of visibility is caused by the decrease of effective display area of a picture.
Generally, although higher pixel density is often necessary for a read picture than a display picture, in the case of the device for reading a color picture with a micro color filter, the problem is that the color picture can not be read with high pixel density since the picture data of a color pixel are obtained by joining three simplex pixels of red, green and blue as described above. Since only the light of the color which is transmitted through a micro color filter is used for the display and for the illumination of an original, it is necessary to increase the quantity of emitted light from a back light source in order to increase the quantity of the transmitted light. Accordingly, the problem is the increase of manufacturing cost by comprising a micro color filter, and additionally, high electric power consumption.
In the case of reading an original picture by irradiating backlight over the whole original as described above in reading the original picture, the problem is that the crosstalk between adjacent pixels gets high and the reslution tends to decline since reflected light from adjacent pixels in the original enters an image sensor. The higher the pixel density in reading is, the greater this problem is.
In regard to this problem, for example, in Japanese Unexamined Patent Publications No. 5-219301, the composition is disclosed wherein an original picture is read so that the adjacent luminescent elements will not emit light simultaneously in the display and read device in which a substrate with such self-luminescent element as EL element, LED and PDP and a substrate with a photo detector are laminated. Even in this case, it is impossible to avoid the deterioration of the visibility and the read property of a picture because of laminating two substrates. Moreover, the problem is that the increase of manufacturing cost and the decrease of yield are caused since it is difficult to form the above-mentioned luminescent element on a substrate.
In order to solve the above-mentioned problems, it is considered that an original picture is read by making liquid crystal a transmission state at each set of pixels which are not adjacent to each other and exposing a photo detector as well as providing a pixel electrode and a photo detector on the same substrate and making common a gate line and a source line at TFT for a pixel electrode and for a photo detector. However, when such charge-storage type as a photodiode is used as the photo detector, there is the possibility of causing the reduction of reading rate by the composition of storing electric charge at the photo detectors of all pixels in each exposing process at each set of pixels.
The present invention, in view of the above-mentioned respects, aims to provide a liquid crystal display device with a function of reading a picture wherein the downsizing of the device, the improvement of operationalization and the decrease of manufacturing cost can be intended without causing the deterioration of visibility, a method of reading a picture by using such liquid crystal display device, and a method of manufacturing such liquid crystal display device.
Moreover, the present invention aims to provide a liquid crystal display device with a function of reading a picture wherein high pixel density in reading can be obtained and the decrease of manufacturing cost and electric power consumption can be intended, and a method of reading a picture by using such liquid crystal display device.
Furthermore, the present invention aims to provide a liquid crystal display device with a function of reading a picture wherein the crosstalk between adjacent pixels can be reduced, the resolution of reading a picture can be improved and high reading rate can be intended, and a method of reading a picture by using such liquid crystal display device.